SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68f90be66e7014c5820cf980698efef9fd9ad41c21432139ecb73a9eab80287e' 
  AND token = 'LikwT4+V7MEBPRUxNPcyH+fKZTqhcr5DKS9lGh6yuIU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}